Global Union is the mandate of the UN - or to give it the UN's parlance: 'global governance'.
The future power structure the UN requires forming a series of ever-consolidating pan-continental regions. The EU is the early template and test-bed. The North American Union should be next.
Every geopolitical step can be recognised as a step towards this resolution, the ambition of which is occulted from the plain view of the uninquisitive, the incurious and the general standard: the outright gullible.
Within these unions the old nation states will be divided into regions. Some small regions could reflect existing national borders, like Scotland. Generally the old nation states will be split-up into regions who will report directly to the Union. There will be no national governments, no need for that level of authority, but there will be geographical 'mega-regions' defined to help with development and such.
The justification is to allow for the scientific management of the world which, they believe, is precluded greatly by the present nation state type of system.
The second major justification is the preclusion of war. Instead of war between one nation and another the whole of humanity will be in the grasp of an soviet socialist authoritarian tyranny, which will be fascist as there will be an elite who operate and own the whole enterprise - which will be nice.